Objectives of the proposed research are to expand knowledge and understanding of the structural components of cellular membrane systems. Emphasis is placed upon continuation of studies on the specific roles of glycolipids in developing cellular structures and in selected cell systems under normal conditions and in derangements such as those which accompany cellular transformation and destructive metabolic error. Details will be sought concerning specific enzymatic interactions between the plasma membranes of intact cells in tissue culture and in isolated synaptic membranes. The information obtained can lead to the development of logical points of attack on diseases of the nervous system and provide new clues to the nature of oncogenic transformation at the cellular membrane level. Goals set for the current year include: a) further characterization of the process of muscle cell fusion, b) purification of Clostridium sialidase and a study of its effect on mammalian cells and selected substrates, and c) determination of turnover periods of synaptic sialomacromolecules. BIBLIOGRAPHIC REFERENCES: I. Barton, N. and Rosenberg, A. Metabolism of Glucosyl-(H3) Ceramide by Human Skin Fibroblasts from Normal and Glucosylceramidotic Subjects. J. Biol. Chem. 250, 3966 (1975).